When taking a digital picture of a scene, the colors of the pixels representing the scene depend on a variation of circumstances, for example, under what sort of lighting conditions the picture is taken and what type of image sensor and/or optics is used for taking the picture. Moreover, the colors in the picture further depend on the spectral power distribution of the objects of the scene. The spectral power distribution of an object describes the proportion of total light emitted, transmitted, or reflected by the object at every visible wavelength.
This may cause a problem in the case when two images are taken of the same scene, but under different lighting conditions, or using different types of image sensors and/or optics, and it is desired to change the appearance of the first image such that it looks like the other image.
US 2012/201451 A1 (Apple Inc) provides a computer program for matching colors of a first image to colors of a second image. The computer program identifies a set of transforms for converting the first image to a device-independent color space. The computer program modifies the set of transforms such that they segment colors of the first image into a set of segmented colors. The computer program applies the modified set of transforms to pixel values of the first image in order to segment the pixels of the first image into the set of segmented colors. In the 451' application, the images are thus segmented based on the colors of the images and the transforms applied to the first image for matching the colors to the second image are based on this segmentation.
However, if the scene comprises objects having different spectral power distributions, transforming each pixel based on the color of the pixel may give an incorrect result. This problem is also known as metamerism.